A deeper look into the Roman society

Initially a number of patricians who were obliged to bring their own horse(s) and equipment. In the late republic this could also be (rich) pleneians. Young men would make their military carreer as an eques. See for example Livius (21.46), where the young P.Cornelius Scipio served as a knight.

Plebeians

Everybody who did not belong to the patrician families or equestrians. Not to be confused with proletarians, the poor, who had not enough possessions to be allowed to serve in the army. There certainly were rich plebeians.

Bit by bit the plebeians would "conquer" the offices. I write conquer because these could be sometimes very vicious and violant actions (from both sides). In time there would arise plebeian nobles, who would hold offices like the patricians.

Elected Roman magistratesDuring the republican era the Roman
society was governed by elected
magistrates.
Most of the magistrates who governed Rome were elected every year. Most
of these functions were doubled: a direct consequence of the Roman
aversion to kings and the fear of the return of a kingdom.

Priesthood
From the early republic on the priesthood
was firmly in the hands of
the patricians (Patres). Since the Roman people were very willing to
listen to the will
of the gods, all of
the Roman society was "under
control" of the patricians.
For example: When a consul was elected, his appointment needed
approval of the gods by means of an augury.
see for instance Livius (22.33) or Livius (23.31)

Prodiges
At the eve of the battle of lake Trasimeno elected consul Gaius
Flaminius left Rome to take command of his legions in Arretium,
before the auguries had been held.
This was seen as a very bad prodigy and the senate was furious.

Struggle of the orders
In the late republic some
of these priesthoods became also accessible for plebeians..

Roman families
Roman society was very paternalistic. The pater
familias was more than just the head of his family. The female
members of this family were
thought to be far less important and
competent than the males. If a family wasn't totally poor it would have at leat one
slave.